This invention relates to the emergency shut down of a section of pipeline and more particularly to a pincer mechanism which is used to crimp pipe on both sides of a break or leak.
Those skilled in the art are aware of the problem of time involved in shutting down a section of pipeline that has developed a break or leak. The gas or liquid in the line is always potentially dangerous and therefore it is important if not critical that the break be isolated and shut off at the earliest possible moment. One current practice is to close the nearest valves in the system on either side of the break in the line. Since the valves in the line may be as much as 15 miles apart, depending upon population density, a substantial amount of damage may be done before the valves can be closed. Also a number of customers may suffer a stoppage or outage if the section shut down is large. Another practice for stopping the leakage is to attach fittings on both sides of the break with which the flow can be stopped or plugged. This also requires time and is dangerous for the workman. Hydraulic hand pumps are also known by which the pipe is crimped but this sort of approach is at least a two man operation and the pressure range and pipe sizes of the hand pumps is quite limited. In any event, a hole or trench must be dug to expose the break which requires 15 to 30 minutes to excavate with a back hoe. Nevertheless, utilities such as gas companies are criticized for the length of time required to close off the leakage and frequently also criticized for the size of the section or length of pipe which is shut down. If the fluid escaping from the pipe is liquid the tendency for the liquid to wash away supporting soil and undermine pipe support increases the danger to workmen. The fact that workers may be required down in the hole or trench is always dangerous whether the escaping fluid is liquid, gas or other vapors.